1. Field of the Invention
The present invention relates to inflatable safety cushion, or airbags, for vehicles. More specifically, the present invention relates to a method and apparatus for restraining side impact airbags to enhance protection against impact and occupant excursion.
2. Description of Related Art
The inclusion of inflatable safety restraint devices, or airbags, is now a legal requirement for many new vehicles. Airbags are typically installed in the steering wheel and in the dashboard on the passenger side of a car. In the event of an accident, an accelerometer within the vehicle measures the abnormal deceleration and triggers the explosion of pressurized gas from an inflator. Expanding gases from the inflator fill the airbags, which immediately inflate to protect the driver and/or a passenger from impact against the windshield, dashboard, and steering wheel.
Side impact airbags have also been developed in response to the need for protection from impact against the side of the vehicle (also known as lateral impact). These airbags, which are commonly referred to as xe2x80x9cinflatable cushionsxe2x80x9d or xe2x80x9cinflatable curtains,xe2x80x9d may be mounted in the vehicle over the doors, and may inflate during an accident to cover the windows, doors, and lateral surfaces of the vehicle. The inflatable cushion may also be connected to tethers that extend from the ends of the airbag to anchoring points within the vehicle. These tethers may exert tension on the inflated cushions to keep the cushions generally between the occupant and the lateral surface of the vehicle.
However, tether systems known in the art have a number of disadvantages. First of all, many known tether systems require that the tether be extended longitudinally away from both ends of the inflatable cushion. Consequently, the front tether must be extended from the front end of the inflatable cushion toward the front of the vehicle and the rear tether must be extended from the rear end of the inflatable cushion toward the rear of the vehicle. Such a design is incompatible with most trucks and sport utility vehicles (xe2x80x9cSUVsxe2x80x9d) in which the passenger compartment of the vehicle ends abruptly behind a lateral surface over which it would be desirable to position a cushion. In these vehicles, there is typically insufficient space for tether extension rearward from the edge of the inflatable cushion.
One of the main purposes in attaching a tethering system to an inflatable cushion is to protect the occupant by applying tension to the inflatable cushion so as to secure the inflatable cushion in the proper position. Without such tension, there is an inherent risk that the inflatable cushion will improperly inflate and injure the occupant. Additionally, during rollover conditions, if the inflatable cushion is not secured into the proper position via tethers, the motion of the occupant may force the inflatable cushion out of an open window, thereby eliminating any possible safety benefits of the inflatable cushion.
While the tethering systems previously known in the art may mitigate some of these problems by tensioning the inflatable cushion, the tensioning force supplied by these systems is sufficient to disjoin the inflatable cushion from its mountings or cause that the inflatable cushion be positioned in a location that does not render the occupant with maximum impact protection.
Using a force sufficient to disjoin or improperly move the inflatable cushion creates various problems. An obvious example of this is that if the inflatable cushion is disjoined from its mountings or improperly positioned, it will no longer be covering the lateral surface of the vehicle, thereby allowing the occupant to sustain injury due to impact against the surface of the vehicle. Likewise, if the inflatable cushion is disjoined from its mountings, it will likely fall on or near the occupant, possibly exposing the occupant to hot gases or toxic substances.
Furthermore, side impact inflatable cushions are often classified according to the compaction process used to compact the inflatable cushion. In general, there are two different categories of cushions: those that are compacted by rolling and those that are compacted by accordion folding. However, many previously known tethering systems are designed for use with a specific compaction process and consequently, cannot be used with either a rolled or an accordion-folded inflatable cushion. Rather, a specific tethering system must often be designed for each type of inflatable cushion. As a result, the cost-effectiveness and interchangeability of known inflatable cushions have suffered somewhat.
Additionally, many known inflatable cushions and tethering systems are not suitable to prevent occupant excursion. xe2x80x9cOccupant excursionxe2x80x9d occurs when the vehicle occupant is ejected from the vehicle, usually through an open door or window, during an accident. Obviously, occupant excursion can be very dangerous, especially during rollover conditions. However, since many known tethering systems can cause the inflatable cushion to be disjoined from its mountings, thereby exposing the window and door of the vehicle, these systems may not provide maximum protection against occupant excursion.
Accordingly, a need exists for a novel tethering system that is suitable for use in vehicles that do not have sufficient interior space behind the inflatable cushion to extend a rear tether. Furthermore, a need exists for such a tethering system that does not require a volatile tensioning device that could improperly deploy and cause injury or impair operation of the inflatable cushion as well as provide maximum protection against occupant excursion.
The apparatus of the present invention has been developed in response to the present state of the art of side impact airbags, and more particularly, in response to the problems associated with inclusion of rear tether systems in vehicles such as trucks and SUVs. In accordance with the invention embodied and broadly described herein, novel tether assemblies along with methods of installing and using such tether assemblies to provide enhanced side impact and rollover protection are disclosed.
The novel systems and methods of the present invention may operate to allow tether systems to be used with side impact airbags in trucks and SUVs. Current tethering systems typically require that the rear tether be extended rear-ward from the rear edge of the window. However, in vehicles such as trucks and SUVs, there is often insufficient space to extend such a tether because the vehicle has an abrupt rear surface immediately rearward of the position at which the airbag is to be installed. By contrast, the current invention enables a manufacturer to use a tethering system for side impact airbags in trucks and SUVs because the rear tether does not have to be extended rearward from the rear edge of the airbag. Through the use of a sliding mechanism, a retractor, and a locking mechanism, the present invention may allow the rear tether to be extended in any direction, while providing the necessary tension.
In one embodiment of the invention, a rear tether is attached at one end to the cushion and at the other end to a rear anchoring point within the vehicle. An intermediate portion of the tether may pass through a sliding mechanism. The intermediate portion of the tether may be configured such that the sliding mechanism can slide along the intermediate portion. The sliding mechanism may also be attached to a retractor configured to exert tension on the sliding mechanism, thereby pulling the intermediate portion toward the retractor. A locking mechanism adjacent to the retractor may ensure that the sliding mechanism cannot move away from the retractor and thereby release the tension on the airbag. The retractor and locking mechanism may thus operate in concert to supply the rear tether with the tension necessary to hold the deployed airbag in its proper place.
In one embodiment of the invention, the retractor is connected to the sliding mechanism via a flexible connector. The retractor may draw the sliding mechanism toward the retractor taking up the flexible connector through simple winding or a similar process. The length of the flexible connector may be selected so that during deployment of the inflatable cushion, there is still slack in the flexible connector. It is only after deployment that the retractor fully removes the slack in the flexible connector. This configuration of the flexible connector may prevent the retractor from exerting a magnitude of force on the airbag that could damage the inflatable cushion during normal operation of the vehicle, disjoin the inflatable cushion from its mountings, or pull the inflatable cushion out of the position designed by the manufacturers to give maximum impact protection.